June 8, 2016 | 3 minute read

Four of every ten women living in the US are now obese, a new high in the obesity epidemic, with rates continuing to be disturbingly high among children, finds two new studies published in JAMA.

The findings by scientists at the Centers for Disease Control are significant for cancer risk and obesity prevention efforts. Aside from not smoking, obesity is the single largest lifestyle factor linked with increased cancer risk. Too much body fat now links to higher risk of 11 cancers, including post-menopausal breast, colorectal, and ovarian.

The study that focused on adults found that in 2014, almost 38 percent of people living in the US were obese overall. That rate is slightly lower for men, with 35 percent obese, and higher for women, at 40.4 percent of women categorized as obese.

Rates of extreme obesity, called class 3 or morbid obesity, followed a similar trend. Overall, almost 8 percent of Americans were categorized as having class 3 obesity, a disease that links to high risks of the many obesity-related conditions like type 2 diabetes, high blood pressure and heart disease. Men had lower rates. But among women, one of every 10 women has class 3 obesity, categorized as a BMI of 40 or more.

The second study find that 17 percent of kids — from toddlers to teens — are obese as well. Extreme obesity affects almost 6 percent of kids overall.

Between 1988 through 2014, obesity generally increased or leveled off in spurts depending upon the age group. At one point among 2 to 5 year olds, obesity rates decreased for a few years to 9 percent, dropping from a high of 14 percent. The study focusing on kids and teens found that 6 percent overall are categorized as extremely obese. Over the past 25 or so years, extreme obesity has increased among children ages 6 to 11 years and among adolescents. There has been no change among children ages 2 to 5 years.

Both reports are based on data from a nationally representative group that are part of the National Health and Nutrition Examination Survey in which participants had their weight and height are measured. Data came from 2005 through 2013-2014 surveys, the most recent information available. For both studies, the authors note that BMI is an imperfect measure of body fat and health risk. And that is especially true among kids, as small changes in weight can lead to relatively large changes in BMI percentile.

An accompanying editorial in by the editors of JAMA points out that these articles join a number of other recent reports highlighting the unrelenting challenge of obesity. “The emphasis has to be on prevention, despite evidence that school- and community-based prevention programs and education campaigns by local governments and professional societies have not been highly successful.” New and creative approaches are needed, the editorial states.

You can calculate your BMI and other measures of body fat here.